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World's Smallest Color Organ 



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World's Smallest Color Organ 

Written By: jduffyl05 

SUMMARY 

This project details the build of a simple SMD LED color organ. A color organ takes audio 
input from a line source, such as an iPod, splits up the audio into frequency bands, and 
pulses colored lights in time with each band. For a more detailed explanation, watch Collin 
Cunningham's "circuit skills" video on color organs. I was inspired to build my own from his 
video, but since I did not have access to all the components he did I had to design my own 
version. 

I suggest buying the components from Jameco. If you buy 100-packs, you can find the 
components, except the board and IC, for just 1 cent each. At that price, the whole unit only 
costs about $10 for the first, then just $3.50 for additional units. 



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World's Smallest Color Organ 



Step 1 — World's Smallest Color Organ 




• The first thing you will need is the materials and tools. All of both can be bought at 
Jameco.com 

• You will need: 

• an SMD LM339 (bought in packs of 5); 

• SMD 1KQ and 470Q resistors (bought in packs of 100 each); 

• SMD 0.1 uF, 0.22uF, and 1uF capacitors (bought in packs of 100 each); (Note: I did not 
have any SMD 1uF capacitors, and I instead used a through-hole version, but it looks far 
better to use all SMD caps.) 

• a collection of resistors or three 500K potentiometers (these cannot be SMD; they must be 
through-hole); 

• SMD red, yellow, and blue LEDs (bought in packs of 100 each); 

• SMD breakout board for 16-pin SMD ICs. Note: this is NOT a prototyping board; it is 
designed to be soldered to. 



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World's Smallest Color Organ 



Step 2 




• Off board components: 

• 3.5mm jack, or other line-level audio input 

• 2 x 3v coin cell battery holder, 4 AAs, or any other power source over 5V 

• Resistor, capacitor or other through-hole leads if you want to pin it on a shirt or lapel 

• Non-momentary switch (any kind, basic power switch) 

• Optional: power indicator LED 



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World's Smallest Color Organ 



Step 3 




• Recommended and needed tools: 
(Note: the file and screwdriver in 
the picture are not useful for this 
project; they are for another.) 

• Soldering iron (needed) 

• Wire cutters (usually needed) 

• Wire strippers (usually needed) 

• Tweezers (recommended) 

• "Fun tack" or "blue tack" used for 
hanging posters. It also helps hold 
down the components, as in Colin 
Cunningham's SMD video 
(recommended) 

• Solder (needed) 

• Magnifier loupe, glass, or other 
magnifying device (recommended) 



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World's Smallest Color Organ 



Step 4 




• Now, solder everything according to the schematic in picture 2. You only need one LED 
per channel, however, not four. Also, if you are using fixed resistors to control the 
frequency response, replace the 500K pots with your choice of resistors. Ignore the 3906 
transistors. Connect the LEDs directly between positive and the comparator outputs. This 
will put about 6V across the LEDs, but the chip cannot deliver enough current to damage 
them, and the voltage is only applied for a tiny fraction of a second. 

• If you notice that the chip is too hot to touch, stop soldering and let it cool down. Too much 
heat will damage the chip. 

• The recommended component layout is shown in the next step. 



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World's Smallest Color Organ 



Step 5 




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• Recommended component layout. 



Step 6 




After soldering the circuit, just add a 6-1 2V source (I used a 9V battery for its compact 
size), and an audio input. Since the audio positive is connected to power ground, you will 
only need three input wires. 
I suggest covering the circuit in epoxy or hot glue to protect it. 



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World's Smallest Color Organ 



Step 7 




• Troubleshooting tips: 

• If the LEDs stay on steadily, check 
the audio connection to the circuit 
itself. Also, make sure the pots or 
large resistors are connected 
between the "+" comparator input 
on the 339 and power "+". 

• If nothing happens, put an LED with 
a resistor across the power pins on 
the LM339 to ensure that power is 
reaching it. Also, turn up the input 
volume, or increase the value of 
the resistors between the LM339 
inputs and power "+". 

• If nothing happens, test your 
batteries first. Even a perfect 
circuit will not work without at least 
3-4V, and it needs current. A 9V 
battery producing 4 V will not power 
this, but a 3.6V battery producing 
3.6V will. 



This project is rated "Difficult" only because it requires circuit-building and SMD soldering. It is 
easy with a little practice in both. 



st generated on 2012-10-31 i 



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Page 7 of 7